U.S. patent number 5,205,125 [Application Number 07/887,962] was granted by the patent office on 1993-04-27 for turbocharged internal combustion engine having exhaust gas pressure actuated turbine bypass valve.
This patent grant is currently assigned to General Motors Corporation. Invention is credited to Michael A. Potter.
United States Patent |
5,205,125 |
Potter |
April 27, 1993 |
Turbocharged internal combustion engine having exhaust gas pressure
actuated turbine bypass valve
Abstract
An internal combustion engine system having reduced high speed
emissions comprising an exhaust driven supercharger having turbine
pressure dependent control means for regulating turbine pressure
and turbine speed to a substantially constant value to produce a
decreasing compressor pressure profile with increasing engine speed
and to reduce mass air flow through the engine during high speed
operation, thereby reducing engine emissions and improving
durability.
Inventors: |
Potter; Michael A. (Livonia,
MI) |
Assignee: |
General Motors Corporation
(Detroit, MI)
|
Family
ID: |
27070195 |
Appl.
No.: |
07/887,962 |
Filed: |
May 26, 1992 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
553018 |
Jul 16, 1990 |
5146753 |
|
|
|
Current U.S.
Class: |
60/602; 137/527;
415/144 |
Current CPC
Class: |
F02B
37/186 (20130101); Y02T 10/12 (20130101); Y10T
137/7898 (20150401); Y02T 10/144 (20130101) |
Current International
Class: |
F02B
37/18 (20060101); F02B 037/12 () |
Field of
Search: |
;60/600-603 ;137/527
;415/144,146,147 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Koczo; Michael
Attorney, Agent or Firm: Barr; Karl F.
Parent Case Text
This is a division of Ser. No. 07/553,018, filed on Jul. 16, 1990,
U.S. Pat. No. 5,146,753.
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. An exhaust driven supercharger for use with an internal
combustion engine comprising a turbine operable by exhaust gas from
said engine, a compressor, driven by said turbine, a turbine inlet
pressure dependent control means operable to regulate exhaust gas
pressure in said turbine, said pressure dependent control means
comprising a turbine wastegate having a valve member actuable, in
response to turbine inlet pressure, to regulate the flow of exhaust
gas through said turbine, a crank member having a first end
operably connected to said valve member, a second end spaced
radially from said first end to define a lever arm between said
ends, biasing means operably connected to said crank member to
exert a closing force on said valve, and radially extending
lost-motion means disposed between said crank member and said
biasing means and operable as said crank member is rotated by the
movement of said valve member from a closed to an opened position,
to vary the effective lever arm between said biasing means and said
valve member and said closing force exerted on said valve by said
biasing means.
2. An exhaust driven supercharger, as defined in claim 1, said
radially extending lost-motion means comprising a slotted opening
in said biasing means, engageable with a sliding member disposed on
said crank member for travel in said slot.
3. An exhaust driven supercharger for use with an internal
combustion engine comprising a turbine operable by exhaust gas from
said engine, a compressor, driven by said turbine, a turbine inlet
pressure dependent control means operable to regulate exhaust gas
pressure in said turbine, said pressure dependent control means
comprising a turbine wastegate having a valve member actuable, in
response to turbine inlet pressure, to regulate the flow of exhaust
gas through said turbine, a crank member having a first end
connected to said valve member, a second end spaced radially from
said first end to define a lever arm between said ends, radially
extending lost-motion means between said first and second ends, and
biasing means operably connected to said lost-motion means to exert
a closing force on said valve, said lost motion means movable
between said first and second ends of said lever as said crank
member is rotated by the movement of said valve member, from a
closed to an opened position, to vary the effective lever arm
between said biasing means and said valve member and said closing
force exerted on said valve by said biasing means.
4. An exhaust driven supercharger, as defined in claim 3, said
radially extending lost-motion means comprising a slotted opening
in said crank member, extending between said first and second end
of said crank member, and having a sliding member disposed therein
for travel in said slot and configured for attachment to said
biasing means.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a turbocharged internal combustion
engine having reduced high speed emissions and, more particularly
to an exhaust driven supercharger having turbine inlet pressure
dependent control means for regulating the compressor pressure
profile.
2. Description of the Relevant Art
Due to the broad speed range of automotive internal combustion
engines, exhaust-gas driven superchargers, or turbochargers, must
be regulated to achieve desired charge-air pressures over wide
ranging engine speeds. Important factors in the design of such
systems are cost, reliability and performance. As a result, the
design should be simple. Conventional turbocharger systems supply
boost to the engine at a progressively increasing rate until a
maximum level is attained; normally in the area of peak engine
torque, see curve "C" of FIG. 2. It is at this level of operation
where the increase in charge density is most useful. Once maximum
compressor pressure out, or boost is achieved, it is regulated to a
constant value by a compressor pressure dependent wastegate.
Maintenance of the compressor pressure at a constant value results
in an increasing turbine pressure profile.
Conventional design turbochargers generally maintain maximum boost
as engine speed increases along a declining torque curve, resulting
in high mass air flow and high average peak cycle pressure during
operating conditions which benefit little from these conditions. It
is generally recognized that NOx exhaust emissions are related to
total engine air flow during high speed, part-load conditions.
Also, durability is closely related to the average peak cycle
pressure of the engine throughout its life. As the average peak
cycle pressure is increased, engine component durability is
affected.
In order to obtain the best compromise between engine emission
performance, engine performance, and engine durability, it is
desirable to apply turbocharger boost only during operating
conditions that benefit from additional charge density.
SUMMARY OF THE INVENTION
In accordance with the present invention, an internal combustion
engine is disclosed for use in automotive applications having an
exhaust driven supercharger, or turbocharger, for compressing the
air being supplied to the engine. The turbocharger compressor
pressure is regulated using turbine inlet pressure dependent
control means which maintain incoming turbine pressure at a
substantially constant or decreasing value once maximum boost is
reached, thereby achieving a decreasing compressor pressure profile
as engine speed increases. Specifically, compressor pressure is
allowed to increase until peak engine torque is reached, at which
time supplied boost is being utilized at optimal conditions. As
engine speed further increases along a declining torque curve,
compressor pressure decreases due to the maintenance of
substantially constant, or decreasing turbine pressure resulting in
lower mass air flow through the engine relative to a conventional
system and, consequently, reduced NOx emissions and increased
durability.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of an internal combustion engine system
embodying the present invention;
FIG. 2 shows the relationship between engine speed, torque and
compressor pressure of conventional engine systems and an engine
system embodying the present invention;
FIGS. 3a and 3b are side and end views respectively, partially in
section, of a first embodiment of the present invention;
FIG. 4 is a partial side view of a second embodiment of the present
invention;
FIGS. 5a and 5b are side and end views respectively, partially in
section, of a third embodiment of the present invention;
FIG. 6 is a partial side view, of a fourth embodiment of the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1 there is shown an internal combustion engine system,
designated generally as 10, comprising a diesel engine 12, having
intake and exhaust manifolds 14 and 16 respectively, and an exhaust
driven supercharger, or turbocharger, 18 connected thereto, in a
well known manner, for compressing the air charge to the engine
intake.
The turbocharger 18 has a compressor portion 20, comprising a
housing 22, an inlet 24 for intake of low pressure air, an impeller
(not shown) disposed within housing 22 for compressing the incoming
air, and an outlet (not shown) in communication with intake
manifold 14 through which the compressed air charge from the
turbocharger is transferred to engine 12. Additionally,
turbocharger 18 has a turbine portion 26, comprising a housing 28,
an inlet 30 in communication with exhaust manifold 16 for
channeling exhaust gas exiting engine 12 into turbine portion 26,
an impeller 32 (see FIG. 3b) disposed within housing 28 which is
acted upon by the exhaust gas passing through turbine portion 26,
and an outlet 34 for directing the exhaust gas to the atmosphere.
The turbine impeller 32 is connected to the compressor impeller by
an impeller shaft (not shown) disposed in shaft housing 36.
In operation, exhaust gas exiting engine 12 through exhaust
manifold 16 enters turbine portion 26 through inlet 30 where it
causes turbine impeller 32 to rotate as it passes through housing
28 and exits through outlet 34. As a result of the mechanical
coupling of turbine impeller 32 with the compressor impeller
through the impeller shaft, the compressor impeller is caused to
rotate, thereby compressing air entering compressor housing 22
through inlet 24 and forcing the compressed air charge through
intake 14 to engine 12. As engine speed and load increases, turbine
inlet pressure rises, resulting in an increase in turbine speed,
and compressor pressure.
To limit turbine speed and compressor pressure as turbine inlet
pressure continues to rise, a wastegate assembly, see FIGS. 3a and
3b, is incorporated into turbocharger 18. The wastegate assembly
comprises a turbine bypass 40, extending between turbine inlet 30
and the outlet 34, for channeling exhaust gas around impeller 32. A
valve seat 42 surrounds the outlet of bypass 40 and a valve member
44 is disposed within turbine outlet 34 to engage valve seat 42
thereby closing bypass 40 and regulating the flow of exhaust gas
therethrough. Operably connected to valve member 44 through arm 50
is valve shaft 46. The valve shaft 46 extends through and is
rotatably supported within opening 48 formed in turbine housing 28.
Exhaust valve 44 pivots about the axis of valve shaft 46 as it
moves into and out of engagement with valve seat 42. A crank member
52 is fixedly connected to the second end of valve shaft 46. The
body of crank member 52 extends radially outwardly from its first
end 54 to terminate at a second end 56 which has attaching means,
such as aperture 58, formed therein.
To control the operation of valve member 44, a biasing assembly,
designated generally as 60, is mounted to supercharger 18 and acts
to exert a closing force on the valve member through crank 52 and
shaft 46. The biasing assembly shown in FIGS. 3a and 3b has a
strut-like configuration comprising a first spring seat 64 which is
fixed relative to supercharger 18, a second spring seat 66,
opposing the first seat and movable relative thereto, and a
compression spring 68 disposed between, and retained by spring
seats 64 and 66. A biasing rod 61, having a first end 62 fixedly
attached to retaining plate 66 by a fastener, such as nut 70,
extends axially through spring 68 and an opening in plate 64 to
attach, at its second end 63, to aperture 58 of crank member
52.
In operation, biasing assembly 60, acts, through crank member 52
and valve shaft 46, to apply a force on valve 44 which normally
urges it into a seated relationship with valve seat 42 thereby
preventing the passage of exhaust gas through turbine bypass 40. As
exhaust pressure within turbine inlet 30 increases with increasing
engine speed, turbine and compressor speed increase thereby
supplying increasing compressor pressure to engine 12, as shown in
curve "T" of FIG. 2. The rate of spring 68 is selected to maintain
valve 44 in a closed position until the turbine inlet pressure
reaches a point corresponding to the maximum desired compressor
pressure. Upon reaching maximum compressor pressure, the turbine
inlet pressure exerts a sufficient opening force on valve 44 to
overcome the closing force exerted thereon by biasing assembly 60
and valve 44 begins to pivot about valve stem 46 to open turbine
bypass 40, allowing exhaust gas to bypass the turbine impeller,
limiting turbine and, consequently, compressor pressure.
Further increases in turbine inlet pressure, corresponding to
continually increasing exhaust pressure within turbine inlet 30,
will further open valve 44. As the valve opens, it rotates valve
shaft 46 and crank member 52 as shown in phantom in FIG. 3a. As
crank member 52 rotates, the effective lever arm between the
biasing assembly 60 and the valve shaft 46 is reduced, thereby
reducing the closing force exerted by biasing assembly 60 on valve
member 44. As a result, the valve member opens at an increasing
rate thereby maintaining a substantially constant or declining
turbine pressure profile and a decreasing compressor pressure
profile as shown in curve T of FIG. 2. The compressor pressure
profile can be tailored to specific applications by varying the
rate of spring 68 and the dimensions of crank member 52.
To achieve an early, rapid decline in the compressor pressure
profile the crank member 52 may be modified as shown in FIG. 6 to
include a radially extending slot 72. The slot allows the second
end 63 of biasing rod 61 to move along the axis of crank member 52
as the crank rotates (as shown in phantom in FIG. 6). The result of
such movement is that as the opening valve member 44 rotates the
crank member 52, the point of application of the closing force
moves toward the axis of rotation of the crank member to further
reduce the effective lever arm between the biasing assembly 60 and
the valve shaft 46. Additionally, movement of the second end 63 of
biasing rod 61 towards the axis of rotation of crank member 52
reduces the force exerted by the spring member 68 on the crank 52.
The result is a substantial decrease in compressor pressure
immediately following the achievement of maximum desired boost.
FIG. 4 shows a second embodiment of the present invention. Similar
parts of the device retain similar numbers from the above
description. In this embodiment, the strut-like configuration of
the biasing assembly is replaced by an extension spring 80 having a
first end attached to anchor 82, which is fixed relative to
turbocharger 18, and a second end attached to the second end 56 of
crank member 52. Attachment may be by means of peg 84 which extends
outwardly from crank member 52. Operation of this embodiment is the
same as that described above for the first embodiment.
A third embodiment of the present invention is shown in FIGS. 5a
and 5b. Similar parts of the device retain similar numbers from the
above description. A torsion spring assembly is employed to exert a
closing force on valve member 44 through crank member 52 and valve
shaft 46. The spring 90 is pivotally supported on retainer 92, with
a first end 96 fastened to anchor 94, which is fixed relative to
turbocharger 18, and a second end 98 attached to the second end 56
of crank member 52 by attaching means such as peg 99. As shown in
FIG. 5a, the second end 98 of torsion spring 90 is configured to
form a slot 100 for sliding engagement with peg 99. As turbine
inlet pressure reaches a level sufficient to open valve member 44
against the closing force exerted by torsion spring 90, valve
member 44 pivots about the axis of shaft 46, as shown in phantom in
FIG. 5a. As the crank rotates, peg 99 slides along the axis of slot
100 to change the effective lever arm between the torsion spring 90
and the valve member 44 thereby reducing the closing force exerted
by the spring on valve member 44 to produce a decreasing compressor
pressure profile as described above. As valve member 44 opens
further, the effective lever arm between the spring and the valve
member continues to decline.
The turbine pressure actuated turbine bypass disclosed, is an
economical solution to undesirably high compressor pressure
profiles during high speed, low torque engine operation.
The crank-biasing means combination provides a desired reduction in
the compressor pressure profile during high speed operations in a
simple, inexpensive, and reliable package, eliminating the need for
expensive electronic control of compressor pressure.
Furthermore, by reducing the compressor pressure at high speed
engine operation, NOx and particulate emissions are reduced due to
the reduction in mass air flow through the engine while engine
durability is increased due to the reduction in average peak cycle
pressure.
While certain embodiments of the invention have been described in
detail above in relation to a turbocharged internal combustion
engine having reduced high speed emissions, it will be apparent to
those skilled in the art that the disclosed embodiment may be
modified. Therefore, the foregoing description is to be considered
exemplary, rather than limiting, and the true scope of the
invention is that described in the following claims.
* * * * *